The research question was that in patients with carious posterior permanent teeth, would the electrical impedance device be as valid as digital radiography in estimation of remaining dentin thickness? The proposed hypothesis was null.

Inclusion Criteria:

• Participants eligible for this study were those aged from 18 y to 28 y,
• willing to join the study
• with clinically detectable occlusal or proximal carious vital permanent molar teeth with closed apex and healthy periodontal supporting.
• The minimum extension of the carious cavity should be at least 1 mm in width to accommodate with the probe of the prepometer

Exclusion Criteria:

• Excluded participants were those with poor oral hygiene,
• severe medical complications,
• showing signs and symptoms of irreversible or necrotic pulp pathology also when the affected tooth was with extended buccal or lingual caries, extending clinically beyond ¼ dentin thickness or previously restored.

The assessors will not be blind about the type of intervention/control assessment methods due to different application methods. However it will not be allowed amongst the examiners to exchange any information throughout the entire study period